Injection molding is commonly used to form plastic articles that are relatively rigid in nature, including containers, medical devices, and so forth. For example, containers for stacks or rolls of pre-moistened wipes are generally formed by injection molding techniques. One problem associated with such containers, however, is that the molding material is often formed from a synthetic polymer (e.g., polypropylene or HDPE) that is not renewable. The use of renewable polymers in an injection molded article is problematic due to the difficulty involved with thermally processing such polymers. Renewable polyesters, for example, have a relatively high glass transition temperature and typically demonstrate a very high stiffness and tensile modulus, while having relatively low impact resistance and low ductility/elongations at break. As an example, polylactic acid has a glass transition temperature of about 59° C. and a tensile modulus of about 2 GPa or more. Nevertheless, the tensile elongation (at break) for PLA materials are only about 5%, and the notched impact strength is only about 0.22 J/cm. Such low impact strength and tensile elongation values significantly limit the use of such polymers in injection molded parts, where a good balance between material stiffness and impact strength is required.
As such, a need currently exists for a renewable polyester composition that is capable of exhibiting a relatively high impact strength and tensile elongation so that it can be readily employed in injection molded articles.